1. Field of the Invention
The present invention relates to a work conveying system and a traveling path sealing structure therefor. In particular, the present invention is concerned with an improvement in a work conveying system and a traveling path sealing structure wherein, in a production line installed within a clean room for the production of, for example, semiconductor components, liquid crystal display panels, medical supplies, drugs, or processed foods, dust generated in the interior of a traveling path (guide rail) in the work conveying system is prevented from leaking out into the clean room, and the work conveying system is adapted to convey a workpiece to each of plural processing stations.
2. Description of the Prior Art
In a semiconductor integrated circuit or a liquid crystal display panel, the deposition of dust causes a lowering of product yield. In the case of medical supplies, drugs and processed foods, it is desirable to produce them in a sterile and sanitary environment. In this connection, intra-clean room production lines are utilized in a wide variety of fields, and various technical developments have been made with respect to various processing chambers and work conveying systems installed within clean rooms.
An overhead traveling type work conveying system which is one type of work conveying system has been developed. According to this work conveying system, the mode of layout of various process devices to be installed within a clean room is not restricted and it is possible to select an optimum layout, that is, it is possible to utilize the interior of the clean room effectively and it is thereby possible to reduce the equipment cost and operation cost of the clean room. The adoption of such an optimal layout is also advantageous in that the work conveying system which can be a source of dust (particles) can be kept separate from apparatuses such as the various processing chambers installed within the clean room.
The present applicant previously invented a work conveying system provided with moving means capable of moving a work holding means arbitrarily in three dimensions in the upper ceiling space within the clean room (see Japanese Patent Laid Open No. 2000-243808).
In applicant""s previous work conveying system, a pair of horizontal fixed guide rails are laid in parallel within a ceiling space and one or plural horizontal traveling guide rails extend between the pair of fixed guide rails and are adapted to travel along the fixed guide rails. On each traveling guide rail is provided a traveling block which can travel along the traveling guide rail. The horizontal moving means includes the fixed guide rails, traveling guide rail(s), and a traveling block. Further, the traveling block is provided with a vertical moving means for moving the work holding means up and down. The three-dimensional moving means is the combination of the horizontal moving means and the vertical moving means.
The fixed and traveling guide rails, which are each in the form of an elongated duct, contain a drive (including a drive motor and a drive mechanism) for the traveling guide rail and the traveling block, also contain a power supply means, and are in communication with each other. Dust (particles) generated from the drive portion and the various slide connections is confined in the ducts which constitute the fixed and traveling guide rails and is evacuated from one end of a communication path and discharged to the exterior of the clean room. In this way contamination of the clean room caused by dust from within the ducts which constitute the guide rails is prevented to a considerable extent.
While the dust present within the ducts is evacuated from one end of the communication path and is discharged to the exterior of the clean room, there is the danger that the dust may leak into the clean room from an elongated gap in the duct, where the drive portion thereof extends through the duct or where a connecting member, for connection between the traveling block and the drive portion, extends through the duct.
FIG. 17 illustrates a sealing structure in this work conveying system, which closes an elongated gap 028 formed to allow for a connecting member 022 which connects a traveling guide rail 015 with a drive section (including a drive motor 023 and a drive roller 026) and extends through a duct 017 from a fixed guide rail 014. In this sealing structure, the connecting member 022 has a zigzag-bent sectional shape and shield plates 041a and 041b are inserted deep into slits 022a and 022b of the connecting member 022, thereby forming a labyrinth to prevent dust generated in the drive and slide portions in the duct from leaking out into the clean room. However, even with such a labyrinth structure, since the dust is evacuated through a long path, it has so far been impossible to completely prevent the dust present in the duct from leaking out into the clean room.
Other examples of overhead traveling type work conveying systems are disclosed in Japanese Patent Laid Open Nos. 1993-116885, 1993-39030, and 1995-291123. In these work conveying systems, a roller provided in a traveling body is adapted to roll on a rail laid on the ceiling. But the drive for the traveling roller is covered with a cover member attached to the traveling body itself, so that dust generated in the drive and in a slide connection between the traveling roller and the rail is released into the clean room. Since the above-described conventional apparatus is not dedicated to a clean room, it is not applicable to a clean room for which a high degree of cleanliness is required.
It is an object of the present invention to solve the above-mentioned problems of the conventional overhead traveling type work conveying system and to provide a work conveying system and a traveling path sealing structure in the work conveying system which can prevent dust generated by a drive mechanism and various slide connections from leaking out into a clean room, the work conveying system comprising fixed guide rails and a traveling guide rail(s), and to thereby prevent a lowering in the degree of cleanliness of the clean room more effectively.
For achieving the above-mentioned object, in a first aspect of the present invention there is provided a work conveying system comprising a least a work holding means for holding a workpiece and a horizontal moving means for moving the work holding means horizontally in an upper ceiling space within a clean room, the workpiece being conveyed to each of plural processing apparatuses, wherein the horizontal moving means has at least one linear moving mechanism, the linear moving mechanism comprising a traveling path covered with a duct and having a guide in the interior of the duct, a traveling body adapted to engage the guide and travel through the interior of the duct, and a slider located on the exterior of the duct and connected to the traveling body for travel together with the traveling body. The work holding means or another linear moving mechanism is attached to the slider, and cleaning means are disposed at suitable intervals along the traveling path to clean the air present within the duct and to discharge the cleaned air to the exterior.
Since the traveling body, which is one component of the linear moving mechanism provided in the horizontal moving means, is adapted to engage the guide located within the duct and to travel along the traveling path therein, dust generated from a slide connection by which the traveling body and the guide are engaged with each other, is confined within the duct and the possibility of its leaking out into the clean room is decreased. Since cleaning means for cleaning air within the duct and discharging it to the exterior are disposed at suitable intervals along the traveling path, dust laden air is evacuated from the duct, cleaned in a unit serving a relatively short traveling path, and the cleaned air is discharged to the exterior. Thus, it is possible to greatly decrease the amount of dust leaking out into the clean room. Consequently, it becomes possible to keep a high degree of cleanliness in the clean room.
In a second aspect of the present invention there is provided, in combination with the above first aspect, a work conveying system wherein a drive source, a drive mechanism, and a power supply means, for driving the traveling body, are accommodated in the interior of the duct, wherein at least the drive source is integral with the traveling body, whereby the possibility of dust generated by the drive portion leaking out into the clean room is decreased. As a result, it becomes possible to keep a higher the degree of cleanliness in the clean room.
In a third aspect of the present invention there is provided, in combination with the above first or second aspect, a work conveying system wherein a base member serving as a base of a guide member constitutes a part of the duct, the guide member and the base member being integrally formed by molding of the same material. In this manner, the guide and the base member which constitute a part of the duct can be fabricated at a low cost, for example, by drawing aluminum.
Further, in a fourth aspect of the present invention there is provided, in combination with any of the above first to third aspects, a work conveying system wherein the horizontal moving means includes a plurality of linear moving mechanisms in combination to permit the horizontal moving means to move arbitrarily in a horizontal plane in the upper ceiling space within the clean room. In this construction, fixed guide rails, each provided with an individual linear moving mechanism, are disposed horizontally in parallel, a traveling guide rail provided with an individual linear moving mechanism is laid between the fixed guide rails so that it can travel along the fixed guide rails, and a traveling block adapted to hold the workpiece is attached to the linear moving mechanism provided in the traveling guide rail so that the traveling block can travel along the traveling guide rail. Thus, a horizontal moving means capable of moving arbitrarily in a horizontal plane in the ceiling space can be constructed in a simple manner.
In a fifth aspect of the present invention there is provided, in combination with any of the above first to fourth aspects; a work conveying system wherein the work holding means is attached to the slider through a vertical moving means for moving the work holding means vertically. This construction provides the work conveying system with a three-dimensional moving means which permits arbitrary movement of the work holding means in a space within the clean room in an extremely simple manner.
In a sixth aspect of the present invention there is provided a work conveying system comprising at least a workpiece holding means for holding a workpiece and a horizontal moving means for moving the work holding means horizontally in an upper ceiling space within a clean room, the workpiece being conveyed to each of plural processing stations, wherein the horizontal moving means has at least one linear moving mechanism, the linear moving mechanism comprising a traveling path defined within a duct and having a guide in the interior of the duct, a traveling body adapted to engage the guide and to travel along the traveling path, and a slider on the exterior of the duct, connected to the traveling body, and adapted to travel together with the traveling body. The work holding means or another linear moving mechanism is attached to the slider. A deformable sealing means is provided in an elongated gap through which extends a connecting member for connecting the slider to the traveling body, the sealing means covering the elongated gap portion without obstructing the travel of the connecting member. Since the traveling body, as one component of the linear moving mechanism provided in the horizontal moving means of the work conveying system, is adapted to engage the guide located within the duct and to travel along the traveling path, dust generated from a slide connection between the traveling body and the guide is confined within the duct and the possibility of its leaking out into the clean room is decreased. Besides, since a deformable sealing means is provided in an elongated gap through which the connecting member extends, the amount of dust leaking out from the elongated gap into the clean room can be greatly decreased. Consequently, it becomes possible to keep a high degree of cleanliness in the clean room.
Further, in a seventh aspect of the present invention there is provided a traveling path sealing structure in a work conveying system, the work conveying system including at least one linear moving mechanism, the linear moving mechanism comprising a traveling path defined within a duct and having a guide in the interior thereof, a traveling body which engages the guide and travels along the traveling path, and a slider exterior to the duct, connected to the traveling body, and adapted to travel together with the traveling body. The work holding means or another linear moving mechanism is attached to the slider. A deformable sealing means is provided in an elongated gap, through which extends a connecting member for connecting the slider to the traveling body, the sealing means covering the elongated gap portion without obstructing the travel of the connecting member. Since the traveling body as one component of the linear moving mechanism provided in the work conveying system is adapted to engage the guide located within the duct and to travel along the traveling path, dust generated by a slide connection between the traveling body and the guide is confined within the duct and the possibility of its leaking out into the clean room is decreased. Besides, since a deformable sealing member is provided in an elongated gap, through which the connecting member extends, it is possible to greatly decrease the amount of dust leaking out through the elongated gap. Consequently, a high degree of cleanliness of the external environment can be maintained.
In an eighth aspect of the present invention there is provided, in combination with the above seventh aspect, a traveling path sealing structure in a work conveying system wherein the sealing means is an expansion member in the shape of bellows which normally extends naturally to seal the elongated gap. According to this construction, by merely providing in the elongated gap portion a bellows-like expansion member which is commonly used as a sealing member or a protective cover member, there can be easily obtained a deformable sealing means which covers the elongated gap without obstructing the travel of the connecting member.
In a ninth aspect of the present invention there is provided, in combination with the above seventh aspect, a traveling path sealing structure in a work conveying system wherein the sealing member is an expansion member which is normally extended by magnetism to seal the elongated gap. According to this construction, by magnetizing a lower edge which extends along the elongated gap and by attracting the lower edge magnetically, the expansion member is extended to cover the elongated gap. Consequently, in the areas other than where the connecting member is located, the sealing of the elongated gap portion is ensured, with no obstruction to smooth travel of the connecting member.
Further, in a tenth aspect of the present invention, there is provided, in combination with the above eighth or ninth aspect, a traveling path sealing structure in a work conveying system wherein, when looking in the traveling direction of the connecting member, in front of the connecting member are provided a first seal holding member for holding the sealing means in an initially closed state and a first seal opening member for subsequently opening the sealing member in advance of the connecting member as it travels through the elongated gap, and at the rear of the connecting member are provided a second seal opening member for holding the sealing means in an initially opened state and a second seal holding member for subsequently closing the sealing member as the connecting member travels through the elongated gap. According to this construction, closure of the elongated gap by the sealing means other than where the connecting member is located and release (opening) of the closure of the elongated gap by the sealing means where the connecting member passes are performed forcibly, so that both positive sealing of the elongated gap and smooth travel of the connecting member can be effected simultaneously.
In an eleventh aspect of the present invention there is provided, in combination with the above seventh aspect, a traveling path sealing structure in a work conveying system wherein the sealing means is a chain which normally hangs down to seal the elongated gap. By providing a chain in the elongated gap, it is possible to easily obtain a deformable sealing means which covers the elongated gap without obstructing the travel of the connecting member.
In a twelfth aspect of the present invention there is provided, in combination with the above seventh aspect, a traveling path sealing structure in a work conveying system wherein the sealing means comprises a pair of upper and lower elastic tubular members which constantly press the connecting member from above and below, and as the connecting member travels along the elongated gap it pushes apart the pair of upper and lower elastic tubular members vertically, while, after passage of the connecting member, the pair of upper and lower elastic tubular members can immediately revert to their original shape. According to this construction, by providing the elongated gap with a pair of upper and lower elastic tubular members having a bellows shape or a balloon shape in section, there is easily obtained a deformable sealing means which covers the elongated gap without obstructing the travel of the connecting member.